Critical role of mitochondrial oxidative stress in acid aspiration induced ALI in mice

Aged garlic therapeutic intervention targeting inflammatory pathways in pathogenesis of bowel disorders

Inflammatory bowel diseases (IBD), which include Crohn's disease and ulcerative colitis, manifest as a result of intricate interactions involving genetic predisposition, environmental factors, intestinal microbiota dynamics, and immune dysregulation, ultimately leading to persistent mucosal inflammation. Addressing this complex pathology requires a nuanced understanding to inform targeted therapeutic strategies. Consequently, our study explored the viability of Aged Garlic Extract (AGE) as an alternative therapeutic regimen for IBD management. Utilizing gas chromatography-mass spectrometry (GC-MS) and scanning electron microscopy (SEM), we characterized AGE, revealing distinctions from Fresh Garlic Extract (FGE), particularly the absence of allicin in AGE and accompanying structural alterations. In In-Vivo experiments employing an IBD rat model, AGE intervention exhibited remarkable antioxidant, antibacterial, and anti-inflammatory properties. Noteworthy outcomes included improved survival rates, mitigation of intestinal damage, restoration of gut microbial diversity, reinforcement of tight junctions, and reversal of mitochondrial dysfunction. Collectively, these effects contributed to the preservation of enterocyte integrity and the attenuation of inflammation. In conclusion, the unique chemical composition of AGE, coupled with its substantial influence on gut microbiota, antioxidant defenses, and inflammatory pathways, positions it as a promising adjunctive therapy for the management of IBD. These observations, synergistically considered with existing research, provide significant insights into the potential utility of AGE in addressing the intricate pathophysiology inherent to IBD. The potential strength of study and rationale of using AGE against IBD includes exploring alternative therapeutic regimens if conventional treatments are associated with side effects, identification of potential hotspots/pathways involved in disease progression and study can provide economically cheaper and naturally occurring alternative to patient community who are struggling to afford expensive medications. These promising findings underscore the necessity for additional investigations to ascertain the feasibility of clinical translation, thereby substantiating the potential therapeutic role of AGE in the management of IBD.

Acute Lung Injury and the NLRP3 Inflammasome

Acute lung injury (ALI) manifests through harm to the capillary endothelium and alveolar epithelial cells, arising from a multitude of factors, leading to scattered interstitial alterations, pulmonary edema, and subsequent acute hypoxic respiratory insufficiency. Acute lung injury (ALI), along with its more serious counterpart, acute respiratory distress syndrome (ARDS), carry a fatality rate that hovers around 30-40%. Its principal pathological characteristic lies in the unchecked inflammatory reaction. Currently, the main strategies for treating ALI are alleviation of inflammation and prevention of respiratory failure. Concerning the etiology of ALI, NLRP3 Inflammasome is essential to the body's innate immune response. The composition of this inflammasome complex includes NLRP3, the pyroptosis mediator ASC, and pro-caspase-1. Recent research has reported that the inflammatory response centered on NLRP3 inflammasomes plays a key part in inflammation in ALI, and may hence be a prospective candidate for therapeutic intervention. In the review, we present an overview of the ailment characteristics of acute lung injury along with the constitution and operation of the NLRP3 inflammasome within this framework. We also explore therapeutic strategies targeting the NLRP3 inflammasome to combat acute lung injury.

Huangqi Baihe Granules alleviate hypobaric hypoxia-induced acute lung injury in rats by suppressing oxidative stress and the TLR4/NF-κB/NLRP3 inflammatory pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Huangqi Baihe Granules (HQBHG) are a modified formulation based on the traditional recipe "Huangqi Baihe porridge" and the Dunhuang medical prescription "Cistanche Cistanche Soup." The Herbal medicine moistens the lungs and tones the kidneys in addition to replenishing Qi and feeding Yin, making it an ideal choice for enhancing adaptability to high-altitude hypoxic environments.

AIM OF THE STUDY

The purpose of this study was to examine a potential molecular mechanism for the treatment and prevention of hypoxic acute lung injury (ALI) in rats using Huangqi Baihe Granules.

MATERIALS AND METHODS

The HCP-III laboratory animal low-pressure simulation chamber was utilized to simulate high-altitude environmental exposure and establish an ALI model in rats. The severity of lung damage was evaluated using a battery of tests that included spirometry, a wet/dry lung ratio, H&E staining, and transmission electron microscopy. Using immunofluorescence, the amount of reactive oxygen species (ROS) in lung tissue was determined. Superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), and myeloperoxidase (MPO) levels in lung tissue were determined using this kit. Serum levels of proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1 beta), and antiinflammatory cytokines like interleukin-10 (IL-10) were measured using an enzyme-linked immunosorbent assay kit. Gene expression changes in lung tissue were identified using transcriptomics, and the relative expression of proteins and mRNA involved in the toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB p65)/Nod-like receptor protein 3 (NLRP3) pathway were determined using western blotting and quantitative real-time PCR.

RESULTS

HQBHG was shown to enhance lung function considerably, decrease the wet/dry ratio of the lungs, attenuate lung tissue damage, suppress ROS and MDA formation, and increase SOD activity and GSH expression. The research also demonstrated that HQBHG inhibited the activation of the TLR4/NF-κB p65/NLPR3 signaling pathway in lung tissue, reducing the release of downstream pro-inflammatory cytokines.

CONCLUSIONS

HQBHG exhibits potential therapeutic effects against ALI induced by altitude hypoxia through suppressing oxidative stress and inflammatory response. This suggests it may be a novel drug for treating and preventing ALI.

Immunomodulatory action of synbiotic comprising of newly isolated lactic acid producing bacterial strains against allergic asthma in mice

Given the reported role of gut-microbiota in asthma pathogenesis, the present work was carried to evaluate immunomodulatory action of newly isolated lactic acid producing bacterial strains Bifidobacterium breve Bif11 and Lactiplantibacillus plantarum LAB31 against asthma using ovalbumin (OVA) based mouse model. Our results show that both strains modulate Th2 immune response potentially through production of short chain fatty acids (SCFAs), resulting in suppression of OVA-induced airway inflammation. Furthermore, synbiotic comprising of both strains and prebiotic, Isomaltooligosaccharide exhibited superior potential in amelioration of OVA-induced airway inflammation through improved modulation of Th2 immune response. Further, synbiotic protects against OVA-induced mucus hyper-production and airway-hyperresponsiveness. Such protection was associated with normalization of gut microbiome and enhanced production of SCFAs in cecum which correlates closely with population of T-regulatory cells in spleen. Overall, our novel synbiotic possesses the ability to fine-tune the immune response for providing protection against allergic asthma.

Elsholtzia bodinieri Vaniot ameliorated acute lung injury in mice by regulating pyroptosis, inflammation, oxidative stress and macrophage polarization

ETHNOPHARMACOLOGICAL RELEVANCE

Elsholtzia bodinieri Vaniot, perennial herbs, a traditional Yunnan Chinese herbal medicine. Its whole herb can be used as commonly used herbs to cure fever, headache, inflammation, indigestion etc., and its tender tip can also be used as tea in Yunnan of China. However, the protective mechanism of Elsholtzia bodinieri Vaniot on acute lung injury (ALI) still needs to be explored.

AIM OF STUDY

ALI is characterized by acute respiratory inflammation, which remains a significant source of morbidity and mortality. The current study with the aim of determining the therapeutic the efficacy of E. bodinieri Vaniot on lipopolysaccharide-induced ALI, moreover uncovered the underlying gene-regulated framework, so E. bodinieri Vaniot might serve as functional food for adjuvant therapy or therapeutic agent.

MATERIALS AND METHODS

These potential pharmacological targets of E. bodinieri Vaniot against ALI were analyzed by multiple bioinformatics databases. E. bodinieri Vaniot methanol extract (EBE) was obtained by ultrasonic-assisted extraction method, and detected by UHPLC-ESI-HRMS/MS. These pyroptosis, inflammation and oxidative stress associated factors were measured using ELISA assay, western blotting, and histopathological examination to assess the effects of EBE. EcoTyper and immunofluorescence staining were employed to estimate macrophage polarization states in ALI lungs tissue.

RESULTS

In ALI lung tissues, EBE treatment could increase B cell leukemia/lymphoma 2 (BCL2) to inhibit pyroptosis, downregulate prostaglandin-endoperoxide synthase 2 (PTGS2) to attenuate inflammation, upregulating NAD(P)H dehydrogenase, quinone 1 (NQO1) to alleviate oxidative stress and induce macrophage polarization toward the M2 phenotype.

CONCLUSION

E. bodinieri Vaniot ameliorated ALI thought regulating pyroptosis, inflammation, oxidative stress and macrophage polarization, as well as could be a promising source for therapeutic agent.

Role of mitochondrial stress and the NLRP3 inflammasome in lung diseases

BACKGROUND

As an organelle essential for intracellular energy supply, mitochondria are involved in intracellular metabolism and inflammation, and cell death. The interaction of mitochondria with the NLRP3 inflammasome in the development of lung diseases has been extensively studied. However, the exact mechanism by which mitochondria mediate the activation of the NLRP3 inflammasome and trigger lung disease is still unclear.

METHODS

The literatures related to mitochondrial stress, NLRP3 inflammasome and lung diseases were searched in PubMed.

RESULTS

This review aims to provide new insights into the recently discovered mitochondrial regulation of the NLRP3 inflammasome in lung diseases. It also describes the crucial roles of mitochondrial autophagy, long noncoding RNA, micro RNA, altered mitochondrial membrane potential, cell membrane receptors, and ion channels in mitochondrial stress and regulation of the NLRP3 inflammasome, in addition to the reduction of mitochondrial stress by nuclear factor erythroid 2-related factor 2 (Nrf2). The effective components of potential drugs for the treatment of lung diseases under this mechanism are also summarized.

CONCLUSION

This review provides a resource for the discovery of new therapeutic mechanisms and suggests ideas for the development of new therapeutic drugs, thus promoting the rapid treatment of lung diseases.

Isolation & identification of anti-inflammatory constituents of Randia dumetorum lamk. fruit: Potential beneficial effects against acute lung injury

ETHNOPHARMACOLOGICAL RELEVANCE

Randia dumetorum Lamk. is an Indian traditional medicinal plant that has been used for the treatment of various disorders including respiratory ailments.

AIM OF THE STUDY

In continuation of our recent report that the Ethanol soluble fraction (ESF) of Randia dumetorum fruit had potent anti-inflammatory activity against acute lung injury (ALI) in mice, the present work was undertaken to unveil the key bioactive constituents possessing anti-inflammatory action against ALI by employing bioactivity-guided fractionation of ESF.

MATERIAL AND METHODS

Different fractions/sub-fractions obtained by column chromatography of ESF were subjected to bioactivity studies by analyzing total and differential count, and protein content in broncho-alveolar lavage fluid (BALF) procured from mice. The most bioactive sub-fraction F3.2 was analyzed for the assessment of various inflammatory mediators using molecular techniques like ELISA, PCR, and western blotting. Further, an attempt was made to separate the key compounds in F3.2 using solvents of differential polarities; and isolated compounds were validated for their anti-inflammatory activity followed by their characterization using spectral techniques like ¹HNMR, ¹³CNMR, FT-IR, and ESIMS Mass Spectrometry.

RESULTS

The column chromatography of ESF yielded four fractions (F1, F2, F3, and F4) and data revealed that maximum activity resides in F3. Further fractionation of F3 yielded sub-fractions F3.1, F3.2, F3.3, and F3.4 which when tested for anti-inflammatory potential, showed F3.2 as the most active one. Moreover, the effect of F3.2 on oxidative stress parameters and inflammatory mediators analyzed via biochemical assays, PCR, and ELISA revealed the proficiency of this fraction in amelioration of ALI. F3.2 was then subjected to recrystallization using different solvents and two pure compounds were isolated which were characterized as D-Mannitol and Oleanolic acid (OA). D-Mannitol did not display any bioactivity, but OA showed potent anti-inflammatory activity.

CONCLUSION

Considering the ethnopharmacological role of R. dumetorum in respiratory ailments, OA as an aglycone moiety seems to be the main active principle possessing anti-inflammatory potential against ALI.

Global Research Trends and Hotspots on Mitochondria in Acute Lung Injury from 2012-2021: A Bibliometric Analysis

BACKGROUND

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a clinical syndrome associated with mitochondria and lacks effective preventive and therapeutic measures. This bibliometric study aims to gain insight into the scientific findings regarding mitochondria in ALI/ARDS.

METHODS

We retrieved the Science Citation Index Expanded (SCIE) of the Web of Science Core Collection (WoSCC) for mitochondria in ALI/ARDS publications from 2012-2021. VOSviewer, CiteSpace (5.8. R3) and Bibliometrix (3.1.4) R package were used for further analysis and visualization.

RESULT

A total of 756 English-language articles and reviews were identified. The annual number of publications presented a rapidly developing trend. China was the most productive and cited country, and the USA had the greatest impact. In the keyword co-occurring network, the terms "acute lung injury", "oxidative stress", "inflammation", "mitochondria" and "apoptosis" occurred most frequently. The co-citation network revealed that #1 mesenchymal stromal cell and #3 endothelial cell had the most bursts of citations. In addition, research hotspots have shifted from "potential therapeutic treatments" and "mitochondrial DNA (mtDNA)" to "endothelial cell" and "mesenchymal stromal cell (MSC)".

CONCLUSION

This bibliometric analysis reveals the research directions and frontier hotspots of mitochondria in ALI/ARDS, which has shown a rapid growth trend in annual publication numbers. mtDNA, mitophagy, and apoptosis have been the most active research areas, while studies on mitochondrial transfer in stem cells have become a hot topic in recent years.

Pulmonary Fibrosis as a Result of Acute Lung Inflammation: Molecular Mechanisms, Relevant In Vivo Models, Prognostic and Therapeutic Approaches

Pulmonary fibrosis is a chronic progressive lung disease that steadily leads to lung architecture disruption and respiratory failure. The development of pulmonary fibrosis is mostly the result of previous acute lung inflammation, caused by a wide variety of etiological factors, not resolved over time and causing the deposition of fibrotic tissue in the lungs. Despite a long history of study and good coverage of the problem in the scientific literature, the effective therapeutic approaches for pulmonary fibrosis treatment are currently lacking. Thus, the study of the molecular mechanisms underlying the transition from acute lung inflammation to pulmonary fibrosis, and the search for new molecular markers and promising therapeutic targets to prevent pulmonary fibrosis development, remain highly relevant tasks. This review focuses on the etiology, pathogenesis, morphological characteristics and outcomes of acute lung inflammation as a precursor of pulmonary fibrosis; the pathomorphological changes in the lungs during fibrosis development; the known molecular mechanisms and key players of the signaling pathways mediating acute lung inflammation and pulmonary fibrosis, as well as the characteristics of the most common in vivo models of these processes. Moreover, the prognostic markers of acute lung injury severity and pulmonary fibrosis development as well as approved and potential therapeutic approaches suppressing the transition from acute lung inflammation to fibrosis are discussed.

Mechanistic Understanding of Lung Inflammation: Recent Advances and Emerging Techniques

Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury characterized by an acute inflammatory response in the lung parenchyma. Hence, it is considered as the most appropriate clinical syndrome to study pathogenic mechanisms of lung inflammation. ARDS is associated with increased morbidity and mortality in the intensive care unit (ICU), while no effective pharmacological treatment exists. It is very important therefore to fully characterize the underlying pathobiology and the related mechanisms, in order to develop novel therapeutic approaches. In vivo and in vitro models are important pre-clinical tools in biological and medical research in the mechanistic and pathological understanding of the majority of diseases. In this review, we will present data from selected experimental models of lung injury/acute lung inflammation, which have been based on clinical disorders that can lead to the development of ARDS and related inflammatory lung processes in humans, including ventilation-induced lung injury (VILI), sepsis, ischemia/reperfusion, smoke, acid aspiration, radiation, transfusion-related acute lung injury (TRALI), influenza, Streptococcus (S.) pneumoniae and coronaviruses infection. Data from the corresponding clinical conditions will also be presented. The mechanisms related to lung inflammation that will be covered are oxidative stress, neutrophil extracellular traps, mitogen-activated protein kinase (MAPK) pathways, surfactant, and water and ion channels. Finally, we will present a brief overview of emerging techniques in the field of omics research that have been applied to ARDS research, encompassing genomics, transcriptomics, proteomics, and metabolomics, which may recognize factors to help stratify ICU patients at risk, predict their prognosis, and possibly, serve as more specific therapeutic targets.

Implication of mitochondrial ROS-NLRP3 inflammasome axis during two-hit mediated acute lung injury in mice

Acute lung injury (ALI) caused by acid aspiration often accompanies bacterial components leading to exaggerated inflammation and can result in acute respiratory distress syndrome (ARDS), but the underlying mechanisms behind such an exacerbation remain unclear. NLRP3 inflammasome and mitochondrial ROS (mtROS) have been implicated in ALI but its role in injury caused through two hit i.e. Hydrochloric acid (HCl) + Lipopolysaccharide (LPS) is not known. Therefore, the present study is designed to elucidate the role of mtROS-NLPR3 inflammasome upon "two-hit" mediated ALI. Our data showed that "two-hit" induced ALI results in aggravated lung inflammation as compared to either of single hit(s) as reflected by a steep increase in inflammatory cells particularly neutrophils in bronchoalveolar lavage fluid (BALF). Further, enhanced inflammation was associated with increased mtROS as depicted by data on mean fluorescence intensity (MFI) of MitoSOX⁺ neutrophils and macrophages in BALF of two-hit simulated mice. Importantly, ALI results in activation of NLRP3 inflammasome as reflected by active caspase-1 protein expression and IL-1β levels. Interestingly, NLRP3 inflammasome inhibitor, MCC950 suppressed the lung inflammation remarkably. Further, Mito-tempo, a mitochondrial-targeted antioxidant, halted "two-hit" mediated NLRP3 inflammasome activation and IL-1β release followed by amelioration of lung inflammation. Suppression in MFI of MitoSOX⁺ stained neutrophils and macrophages by Mito-tempo was associated with down-regulation of phospho-p65-NF-κB and its dependent genes (IL-1β/TNF-α/IL-6). Overall, our data suggest that NLRP3 inflammasome activation by mtROS plays a critical role in pathogenesis of exaggerated inflammation and therefore targeting mtROS-NLRP3 inflammasome axis may be an attractive option for combating ALI/ARDS.

Antioxidants as Therapeutic Agents in Acute Respiratory Distress Syndrome (ARDS) Treatment-From Mice to Men

Acute respiratory distress syndrome (ARDS) is a major cause of patient mortality in intensive care units (ICUs) worldwide. Considering that no causative treatment but only symptomatic care is available, it is obvious that there is a high unmet medical need for a new therapeutic concept. One reason for a missing etiologic therapy strategy is the multifactorial origin of ARDS, which leads to a large heterogeneity of patients. This review summarizes the various kinds of ARDS onset with a special focus on the role of reactive oxygen species (ROS), which are generally linked to ARDS development and progression. Taking a closer look at the data which already have been established in mouse models, this review finally proposes the translation of these results on successful antioxidant use in a personalized approach to the ICU patient as a potential adjuvant to standard ARDS treatment.

Ramelteon protects against human pulmonary microvascular endothelial cell injury induced by lipopolysaccharide (LPS) via activating nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway

Acute lung injury (ALI) is classified as a moderate or mild acute respiratory distress syndrome and is a prominent cause of morbidity and mortality among the critically ill population. Ramelteon is a melatonin receptor agonist with anti-inflammatory and antioxidant effects. The current study investigated the role of ramelteon in lipopolysaccharide (LPS)-induced human pulmonary microvascular endothelial cells (HPMECs) and its potential regulatory mechanisms. A CCK-8 assay was used to examine the effect of ramelteon on the viability of LPS-induced HPMECs, HPMECs treated with ML385 [a Nrf2 inhibitor] and HPMECs treated with SnPP [a HO-1 inhibitor]. The Nrf2/HO-1 signaling pathway was additionally assessed by performing Western blotting. The levels of oxidative stress and inflammatory cytokines in HPMECs were detected using kits and reverse transcription-quantitative PCR. Cell apoptosis was evaluated via TUNEL staining. Furthermore, cell permeability was assessed using a FITC-dextran fluorescent probe, ZO-1 and occludin expression was determined via Western blotting. The results demonstrated that ramelteon elevated HPMEC viability after LPS stimulation. Additionally, ramelteon markedly reduced LPS-induced oxidative stress, inflammation and apoptosis. Moreover, cell permeability was notably decreased in ramelteon-treated groups and was accompanied by upregulated ZO-1 and occludin expression. Ramelteon treatment also activated the Nrf2/HO-1 signaling pathway in LPS-induced HPMECs. Furthermore, the addition of ML385 or SnPP reversed the protective effects of ramelteon on LPS-induced oxidative stress, inflammation, apoptosis and cell dysfunction in HPMECs. Collectively, the results suggested that ramelteon alleviated LPS-induced HPMEC damage by activating the Nrf2/HO-1 signaling pathway, making it an effective treatment for ALI.

Mitochondrial dynamics and mitophagy in lung disorders

Mitochondria are biosynthetic, bioenergetic, and signaling organelles which are critical for physiological adaptations and cellular stress responses to the environment. Various endogenous and environmental stress affects critical processes in mitochondrial homeostasis such as oxidative phosphorylation, biogenesis, mitochondrial redox system which leads to the formation of reactive oxygen species (ROS) and free radicals. The state of function of the mitochondrion is particularly dependent on the dynamic balance between mitochondrial biogenesis, fusion and fission, and degradation of damaged mitochondria by mitophagy. Increasing evidence has suggested a prominent role of mitochondrial dysfunction in the onset and progression of various lung pathologies, ranging from acute to chronic disorders. In this comprehensive review, we discuss the emerging findings of multifaceted regulations of mitochondrial dynamics and mitophagy in normal lung homeostasis as well as the prominence of mitochondrial dysfunction as a determining factor in different lung disorders such as lung cancer, COPD, IPF, ALI/ARDS, BPD, and asthma. The review will contribute to the existing understanding of critical molecular machinery regulating mitochondrial dynamic state during these pathological states. Furthermore, we have also highlighted various molecular checkpoints involved in mitochondrial dynamics, which may serve as hopeful therapeutic targets for the development of potential therapies for these lung disorders.

Redox Role of ROS and Inflammation in Pulmonary Diseases

Reactive oxygen species (ROS), either derived from exogenous sources or overproduced endogenously, can disrupt the body's antioxidant defenses leading to compromised redox homeostasis. The lungs are highly susceptible to ROS-mediated damage. Oxidative stress (OS) caused by this redox imbalance leads to the pathogenesis of multiple pulmonary diseases such as asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory distress syndrome (ARDS). OS causes damage to important cellular components in terms of lipid peroxidation, protein oxidation, and DNA histone modification. Inflammation further enhances ROS production inducing changes in transcriptional factors which mediate cellular stress response pathways. This deviation from normal cell function contributes to the detrimental pathological characteristics often seen in pulmonary diseases. Although antioxidant therapies are feasible approaches in alleviating OS-related lung impairment, a comprehensive understanding of the updated role of ROS in pulmonary inflammation is vital for the development of optimal treatments. In this chapter, we review the major pulmonary diseases-including COPD, asthma, ARDS, COVID-19, and lung cancer-as well as their association with ROS.

Orientin relieves lipopolysaccharide-induced acute lung injury in mice: The involvement of its anti-inflammatory and anti-oxidant properties

Oxidative stress and inflammatory responses are nearly involved in the pathogenesis of various diseases, including acute lung injury (ALI). Orientin (Ori), a flavonoid component extracted from natural plants, displayed anti-inflammatory and antioxidant properties in our previous studies. In the current study, we aimed to investigate the amelioration effect of Ori on lipopolysaccharide (LPS)-induced ALI, and we further explored the potential molecular mechanisms. The present results indicated that Ori effectively alleviated LPS-induced ALI by improving the histological changes of lung; decreasing the lung W/D ratio and protein levels, the release of inflammatory cells and cytokines into the bronchoalveolar lavage fluid (BALF); inhibiting nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and high mobility group box 1 (HMGB1) protein expression; reducing malondialdehyde (MDA) formation and reactive oxygen species (ROS) generation; and increasing the content of glutathione (GSH) and superoxide dismutase (SOD) contents. Moreover, Ori treatment not only significantly suppressed the LPS-induced nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome, and nuclear factor-kappa B (NF-κB) signaling pathway activation, but also obviously restored the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), NAD (P) H: quinone oxidoreductase (NQO1), glutamate-cysteine ligase catalytic (GCLC), and heme oxygenase 1 (HO-1) expression in the lung; all of which are reduced by LPS. Taken together, these data suggested that Ori plays an important role in the protection against ALI by suppressing inflammation and oxidative stress which may be strongly related to the suppression of NLRP3 inflammasome and NF-κB activation, as well as the upregulation of the Nrf2 signaling pathway.

Inflammasome activation in acute lung injury

Inflammasomes are multiprotein complexes tasked with sensing endogenous or exogenous inflammatory signals and integrating this signal into a downstream response. Inflammasome activation has been implicated in a variety of pulmonary diseases, including pulmonary hypertension, bacterial pneumonia, COPD, and asthma. Of increasing interest is the contribution of inflammasome activation in the context of acute lung injury/acute respiratory distress syndrome (ALI/ARDS). Inflammasome activation in both the lung parenchyma and resident immune cells generates intereukin-1β (IL-1β) and IL-18, both of which drive the cascade of lung inflammation forward. Blockade of these responses has been shown to be beneficial in animal models and is a focus of translational research in the field. In this review, we will discuss the assembly and regulation of inflammasomes during lung inflammation, highlighting therapeutically viable effector steps. We will examine the importance of IL-1β and IL-18, two key products of inflammasome activation, in ALI, as well as the contribution of the pulmonary endothelial cell to this process. Finally, we will explore translational research moving toward anti-inflammasome therapies for ALI/ARDS and speculate toward future directions for the field.

Pulmonary pyruvate metabolism as an index of inflammation and injury in a rat model of acute respiratory distress syndrome

Increased pulmonary lactate production is correlated with severity of lung injury and outcome in acute respiratory distress syndrome (ARDS) patients. This study was conducted to investigate the relative contributions of inflammation and hypoxia to the lung's metabolic shift to glycolysis in an experimental animal model of ARDS using hyperpolarized (HP) ¹³ C MRI. Fifty-three intubated and mechanically ventilated male rats were imaged using HP ¹³ C MRI before, and 1, 2.5 and 4 hours after saline (sham) or hydrochloric acid (HCl; 0.5 ml/kg) instillation in the trachea, followed by protective and nonprotective mechanical ventilation (HCl-PEEP and HCl-ZEEP) or the start of moderate or severe hypoxia (Hyp90 and Hyp75 groups). Pulmonary and cardiac HP lactate-to-pyruvate ratios were compared among groups for different time points. Postmortem histology and immunofluorescence were used to assess lung injury severity and quantify the expression of innate inflammatory markers and local tissue hypoxia. HP pulmonary lactate-to-pyruvate ratio progressively increased in rats with lung injury and moderate hypoxia (HCl-ZEEP), with no significant change in pulmonary lactate-to-pyruvate ratio in noninjured but moderately hypoxic rats (Hyp90). Pulmonary lactate-to-pyruvate ratio was elevated in otherwise healthy lung tissue only in severe systemic hypoxia (Hyp75 group). ex vivo histological and immunopathological assessment further confirmed the link between elevated glycolysis and the recruitment into and presence of activated neutrophils in injured lungs. HP lactate-to-pyruvate ratio is elevated in injured lungs predominantly as a result of increased glycolysis in activated inflammatory cells, but can also increase due to severe inflammation-induced hypoxia.

Gallic acid ameliorates COPD-associated exacerbation in mice

COPD is an inflammatory lung disease, which is often exacerbated with microbial infections resulting in worsening of respiratory symptoms. Gallic acid (GA), a naturally occurring phenolic compound is known to possess anti-oxidant/anti-inflammatory activity. We have recently reported that GA protects against the elastase (ET) induced lung inflammation and emphysema and the present work was designed to investigate the beneficial effects of Gallic acid against ET + Lipopolysachharide (LPS) induced COPD exacerbation like condition in mice model. Our data showed that i.t. administration of LPS at 21 days after ET instillation resulted in significant infiltration of inflammatory cells particularly neutrophils (p < 0.0001) into the lungs along with elevated levels of pro-inflammatory cytokines like TNF-α, IL-1β and IL-6 (p < 0.0001). Interestingly, daily administration of GA (200 mg/Kg b. wt.) starting 7 days before ET instillation, significantly blunted the ET + LPS induced inflammation as indicated by reduced number of inflammatory cells particularly neutrophils (p < 0.0001) in BALF along with suppression of myeloperoxidase activity (p = 0.0009) and production of pro-inflammatory cytokines (p < 0.0001). Further, GA also restored the redox imbalance in the lungs towards normal. Additionally, phosphorylation of p65-NF-κB was found to be reduced (p = 0.015), which was associated with downregulation in the gene expression of IL-1β (p = 0.022) and TNF-α (p = 0.04). Conversely, GA treatment resulted in increased protein levels of Nrf2 (p = 0.021) with concomitant increase in transcription of its downstream target genes HO-1 (p = 0.033) and Prdx-1 (p = 0.006). Overall, our data show that GA effectively modulates COPD exacerbation manifestations in mice potentially by restoring redox imbalance in lungs.